EP 13836 discloses emulsion copolymers, which comprise (i) 20 to 69.5% by weight of (meth)acrylic acid, (ii) 0.5 to 25% by weight of a monomer of the formula CH2═C(R)—C(O)—(CH2CH2O)n—R0, in which R is H or CH3, n is at least 2 and R0 is C8-C30-alkyl, and (iii) at least 30% by weight of a C1-C4-alkyl(meth)acrylate. Following neutralization with alkali, these copolymers serve as thickeners for coating compositions, detergents and the like.
WO 99/65958 describes alkali-soluble thickeners, which comprise the reaction product of an unsaturated carboxylic acid, of a monoethylenically unsaturated monomer and of a hydrophobic, alkoxylated macromonomer. The monoethylenically unsaturated monomer comprises a methyl group; preferably, this is methyl acrylate. These polymers are said to become soluble at pHs of just 4.5 to 6.0 and are therefore suitable for cosmetic products.
WO 2006/016035 relates to the use of a water-soluble acrylic polymer as thickener in pigmented aqueous preparations. The acrylic polymer consists of an ethylenically unsaturated monomer with carboxyl function, an ethylenically unsaturated nonionic monomer and an ethylenically unsaturated oxyalkylated monomer, which is terminated with a hydrophobic non-aromatic branched chain having 10 to 24 carbon atoms.
WO 2009/062994 relates to a process for the preparation of an aqueous thickener dispersion from a monomer composition which comprises:                a) at least one ethylenically unsaturated carboxylic acid, and        b) at least one ethylenically unsaturated hydrophobic monomer, where                    (i) an at least partially polymerized pre-emulsion is prepared from 10 to 80% by weight, preferably 40 to 70% by weight, of the monomer composition and            (ii) the remainder of the monomer composition is added in its entirety to the at least partially polymerized pre-emulsion and a free-radical polymerization is initiated.                        
The preparation of polymers with comparatively large amounts of carboxyl groups by the route of conventional emulsion polymerization often leads to the formation of coagulate or wall deposit within the reaction space, as a result of which the preparation process is generally hindered considerably.
The formation of finely divided coagulate, also referred to as microcoagulate or specks leads, inter alia, to the blockage of the filters used in the work-up of the dispersions. Specks cannot be seen in the liquid dispersion with the naked eye, but can generally not be separated off by conventional filtration. They adversely affect the further processing of the dispersions such as, for example, the manufacture of cosmetic preparations.